The Anorectal Manometry Procedure

Doctor talking to patient about results
John Fedele/Blend Images

Anorectal manometry is a diagnostic procedure that measures the muscle tone of the sphincters and other muscles in your anus and rectum. This information can be used by your doctor to better understand and treat any problems you may be having with your bowel movements.

A rectal balloon expulsion test may accompany the anorectal manometry procedure. Specifically, these tests assess:

  • The coordination of the rectal and anal muscles
  • The reflex action of the rectal and anal muscles
  • Sensations within the rectum
  • The strength and weakness of the anal and rectal muscles

Anorectal manometry is considered to be a safe, low-risk procedure, but there are some questions about its clinical usefulness. Some argue that the diagnosis of defecation disorders can be made based on symptom report only. The use of new technology, i.e. the use of high-resolution and high-definition catheters, is hoped to bring about improvements in the validity and usefulness of test results, although research has not yet fully supported this hope.

What Is Anorectal Manometry Used For?

Anorectal manometry might be recommended to you if you have one of the following health problems:

  • Chronic constipation
  • Dyssynergic defecation.
  • Fecal incontinence (soiling)

Tightness of the sphincter muscles during a bowel movement can contribute to constipation, while weakness in the sphincter muscles can lead to fecal incontinence. Anorectal manometry can tell whether these muscles are working as they should.

What to Expect During the Procedure

Prior to the procedure, you most likely will not have to undergo a full colonoscopy prep, but you will most likely be asked to give yourself an enema.

The test itself is not painful. It involves the insertion of a small, flexible probe into your rectum while you are lying on a table. If you are having the balloon expulsion test, a small balloon will be inserted into your rectum and slowly filled. You may be asked at various times to relax or squeeze your rectal muscles or to push down as if having a bowel movement. The test typically takes approximately 30 minutes to one hour.

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